I would say sure to the laser lance in there also, it would really help take out those evil MC's or IC's that creep into these low point games. However, I don't really think he'd live to do it. At start you have 6 models on the board, probably grouping the autrarch with the jetbikes for the extra wounds. That is enough potential fire coming his way if he did split off to attack that it wouldn't be good. I'd try to find the points for a reaper launcher (i just know i am going to catch flak for saying that). A RL will let you stay back with your jetbikes and soften the units that the DA will be attacking. The serpent can handle the antitank most likely or at least draw off enough fire. Besides the Autrarch still has haywire grenades just in case. You have the DA set up for up close stormy goodness, but without storm or doom you aren't going to kill many marines. If you could find a way to squeeze in blade storm it would probably pay off. Heck I would even consider dropping a couple models out of the unit.
Strat is simple. Go up with all and shoot, jetbikes-autrarch at troops and waveserpent at armor/MC. enemy moves closer, could be in range of serpent and bikes so expect a hand full of shots, not many though. Serpent moves up and drop DA next to him, no blocking LoS. All shoot same troop except the armor hunting serpent, bladestorming. Hopefully that is at least one troop down. Turn 3 DA reboard serpent, Jetbikes start picking on other troop. Serpent repeats, or helps (if alive). With any luck turn 4 will look like turn 2, save a couple stragglers and you can pick on the hq. Just remember to have your jetbikes get to home objective on turn 5. DA in a serpent can hold another if more than 2. Enemy low on troops will have to struggle. That is taking the extreme optimist route.